Searching for relevant information in a computer network such as the Internet is a complex task for which many different techniques have been applied. In many cases, conventional search algorithms may be useful in locating documents such as web pages that contain certain keywords.
Many websites may purport to express opinions or state facts about certain issues, products, services, or other items. Because the websites may be created by anyone, and the costs of producing such a website has very low overhead, the validity of the opinions or facts may be questionable unless the producer of the website has credibility.
The credibility of statements made on various websites may be unknown. For example, someone may use several anonymous email aliases to add comments praising a product on a website just to bolster the product's reputation. Because many such comments are essentially anonymous or unknown, it may be hard to tell if the comments are from actual owners of the product or from the advertiser posing as an owner.